Such an installation essentially comprises a silencer, generally in the form of an elongate cylindrical body disposed downstream from the engine which is to be tested on the ground, which silencer collects the exhaust gases from the engine, cools them, and dumps them into the atmosphere after attenuating the exhaust noise. A conventional silencer of this type is entirely suitable for conventional engines that eject their exhaust gases along the longitudinal axis of the engine.
However, manufacturers are currently developing a new generation of jet engines, i.e. engines whose outlet nozzles are steerable relative to the longitudinal axes of said engines. When the jet of gas from the engine, or when the nozzle of the engine under test, is at an angle relative to said longitudinal axis (so-called "vector" operation), the end portion of the silencer closest to the engine is exposed to very high temperatures, of about 2000.degree. C., at least in the portion thereof which is struck directly by the jet of exhaust gases, and most conventional metals and alloys cannot withstand such temperatures.
Document FR-A-2 633 011 describes a solution to this problem, comprising a ground testing installation for an aircraft jet engine having a nozzle that is steerable relative to the longitudinal axis of said engine, the installation comprising:
a silencer having a body that is generally in the form of an elongate cylinder and intended to be disposed behind the nozzle of said engine; and PA1 a funneling device for funneling the jet of exhaust gases from the engine, which device is disposed between the engine and the silencer, said device comprising a generally cylindrical outer shell which flares in the vicinity of its end for facing the engine under test, and a generally cylindrical inner shell which is concentric with said outer shell and is intended to deflect the jet of exhaust gases when said jet or the nozzle of the engine under test is at some angle of inclination relative to the longitudinal axis of said engine. More particularly, in that case, the inner shell includes a coil for conveying a flow of cooling fluid such as water, and extending generally along the cylinder generator lines formed by said inner shell. That solution provides satisfaction firstly, because of the effect of the inner shell, by the time the jet of exhaust gases from the engine reaches the silencer per se disposed downstream of said device in the flow direction of said jet, the jet is again at least substantially parallel to the longitudinal axis of the silencer and therefore does not run the risk of striking the walls thereof, and secondly, since the inner shell is cooled, there is no need to use special refractory materials to make said shell, e.g. ceramics that are heavy, fragile, and expensive, and the shell may be made merely of steel. PA1 firstly the presence on the test site of a sufficient quantity and quality of cooling liquid such as water, for example; and PA1 secondly the installation of an assembly for treating and/or cooling the heated fluid leaving the coil.
However, that solution that makes use of a forced flow of cooling fluid through a coil suffers from the drawback of requiring:
An object of the present invention is to avoid the above drawback.